The present invention is directed toward semiconductor circuits, and more particularly to phase change memory cells and methods for fabrication such cells.
Programming a phase change memory cell generally requires passing a program current through phase change material. The program current causes some or all of the phase change material to melt. It is generally desirable to reduce the program current needed to melt the phase change material. Typically, smaller program currents require smaller access transistors. Smaller access transistors allow for a higher memory cell density in a given wafer die.
Traditional approaches to reducing the program current include reducing the cross sectional area of memory cell electrodes and/or increasing the resistivity of the electrode material. Other approaches include increasing the resistivity of the phase change material.